09-retrieving-runtime-types.md

Retrieving Runtime Types

1. On the Github API, try running a query like this. Should it execute?

   {
     node(id: "U_kgDOAAi8FQ") {
       id
       __typename
       login
       name
     }
   }
   

2. We asked for an interface type (Node), and even though it may have returned a User, we can't retrieve that User's login or name, because they're not defined on Node, the interface type.

   To include fields based on their runtime type, we can use fragments.

3. Create a fragment to query the login and name fields, and then 'call' it from your query using the spread operator. What happens?

4. Run the same query and fragment again, but with a different id (eg O_kgDOAA3wnw) that retrieves a different type. What response do you get? Do you get an error?

5. How could you retrieve a login and name if a User is returned, but a description, name and location if an Organization is returned? Try it.